Conductance in Co/Al[subscript 2]O[subscript 3]/Si/Al[subscript 2]O[subscript 3] permalloy with asymmetrically doped barrier
Name
Guerrero-2010-Conductance in CoAl2O3SiAl2O3 permalloy with asymmetrically doped barrier.pdf
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911.05 KB
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Author(s)
Guerrero, R.
Aliev, F. G.
Villar, R.
Santos, Tiffany S.
Moodera, Jagadeesh
Dugaev, V. K.
Barnas, J.
Date Issued
January 2010
Journal
Physical Review B
Publisher
American Physical Society
Citation
Guerrero, R. et al. "Conductance in Co/Al2O3/Si/Al2O3 permalloy with asymmetrically doped barrier." Physical Review B 81.1 (2010): 014404. © 2010 The American Physical Society
Version
Final published version
Abstract
We report on dependence of conductance and tunnelling magnetoresistance on bias voltage at different temperatures down to 2 K in Co|Al[subscript 2]O[subscript 3](10 Å)|Si(δ)|Al[subscript 2]O[subscript 3](2 Å)|Permalloy magnetic tunnel junctions. Complementary low frequency noise measurements are used to understand the conductance results. The obtained data indicate the breakdown of the Coulomb blockade for thickness of the asymmetric silicon layer exceeding 1.2 Å. The crossover in the conductance, the dependence of the tunneling magnetoresistance with the bias voltage and the noise below 80 K correspond to one monolayer coverage. Interestingly, the zero bias magnetoresistance remains nearly unaffected by the presence of the silicon layer. The proposed model uses Larkin-Matveev approximation of tunneling through a single impurity layer generalized to three-dimensional case and takes into account the variation of the barrier shape with the bias voltage. The main difference is the localization of all the impurity levels within a single atomic layer. In the high thickness case, up to 1.8 Å, we have introduced a phenomenological parameter, which reflects the number of single levels on the total density of silicon atoms.
MIT Department
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.81.014404
